Modified Project Summary/Abstract Section: Non-viral gene therapy is a promising approach to treating myocardial ischemia where the supply of oxygen and nutrients are blocked due to blockage in the blood vessels. Vascular Endothelial Growth Factor (VEGF) can trigger new blood vessel formation. Thus, one of the gene therapy strategies for treating myocardial ischemia is to graft mesenchymal stem cells (MSCs) with VEGF transfected in damaged heart tissue not only because the expressed VEGF can induce the formation of new blood vessels to supply the required oxygen and nutrients but also because MSCs can differentiate into heart muscle cells and revive the damaged tissue. Our long-term goal is to integrate biomolecular recognition and nanotechnology to build target-specific non-viral nano-vectors that can deliver VEGF gene to heart for treating myocardial ischemia. The objective of this application is to mimic the structure of phage to assemble target-specific peptides selected by phage display and a VEGF gene-tethered superparamagnetic nanoparticle into a phage-like nanoparticle for VEGF gene delivery. The overall hypotheses of this project are that phage display selected peptides that can target MSCs can be integrated into the VEGF gene-tethered superparamagnetic nanoparticles with cell-specific peptide motif protruding from the surface by a self-assembly process and the resultant multi-functional phage-like nanoparticle will have desired cell-specificity and improved efficiency of VEGF gene transfer into MSCs. Aim 1 is to select a peptide that can be specifically internalized into MSCs by using phage display technology. Aim 2 is to integrate cell-targeting peptides into VEGF gene-tethered superparamagnetic nanoparticles to build phage-like nanoparticles with cell-specific peptide motifs protruding from the surface through self-assembly. Aim 3 is to evaluate the stability, cytotoxicity, cell-specificity and transfection efficiency of the nanoparticles with and without an external magnetic field. Successful completion of this project will enable the development of a new gene therapy strategy for treating diseases that require VEGF expression to induce new blood vessel formation.